Evidence for a Nodal-Line Superconducting State in LaFePO
Evidence for a Nodal-Line Superconducting State in LaFePO
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DOI：
10.1103/physrevlett.102.147001
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发表时间：
2009-04-10
影响因子：
8.6
通讯作者：
Carrington, A.
中科院分区：
文献类型：
--
作者：
Fletcher, J. D.;Serafin, A.;Carrington, A.
在一些砷化铁超导体中，有强有力的证据表明存在完全间隙的超导态，这种超导态要么符合传统的s波对称，要么符合不寻常的s（+/-）态，其中电子和空穴费米表面片之间的间隙改变了符号。在这里，我们报告了在非常干净的相关磷化铁超导体LaFePO样品中，在温度降至接近100 mK时的穿透深度lambda(T)的测量结果。我们发现lambda(T)与T近似线性变化，这强烈表明该化合物中存在间隙节点。结合其他数据，这表明间隙函数并非适用于所有的粒子超导体。
In several iron-arsenide superconductors there is strong evidence for a fully gapped superconducting state consistent with either a conventional s-wave symmetry or an unusual s(+/-) state where the gap changes sign between the electron and hole Fermi-surface sheets. Here we report measurements of the penetration depth lambda(T) in very clean samples of the related iron-phosphide superconductor, LaFePO, at temperatures down to similar to 100 mK. We find that lambda(T) varies approximately linearly with T strongly suggesting the presence of gap nodes in this compound. Taken together with other data, this suggests the gap function is not universal for all pnictide superconductors.